Infection The disease has been spreading widely due to extensive planting of highly susceptible varieties
The cereal disease Fusarium graminearum is a fungal species that is found all around us. Fusarium is a large grouping with many species, and it occurs naturally in the soil. Fusarium graminearum is the fungal infection that causes fusarium head blight in wheat, oats, barley and corn, and it is the most aggressive fusarium species causing head blight.
“Fusarium graminearum is a problem because the causative agent itself damages kernel development, and that affects grade and yield,” says Harry Brook, crop specialist with Alberta Agriculture and Rural Development. “Also, it has a significant negative effect on the quality of grain used for feed, malting, milling, biofuel (ethanol) and brewing. More importantly, fusarium-affected grain may contain fungal toxins (mycotoxins), such as deoxynivalenol (DON or vomitoxin), which are highly poisonous to livestock and humans above certain threshold levels.”
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This disease has been spreading widely due to extensive planting of highly susceptible varieties, especially in durum wheat. Zero tillage has also contributed to the spread of the disease as infected crop residue from previous crops (especially with short rotations), are the prime source of head blight infection. Corn in rotation is known to be highly susceptible and can be instrumental in the spread of fusarium to cereal crops.
“Probably the greatest reason for the increased spread in Alberta has been the weather conditions at heading,” says Brook. “Warm, moist conditions at heading in combination with the airborne spores, has led to increased incidence and severity of the disease in Alberta. Once it is established, fusarium easily overwinters on infected crop residues and on infected seed, providing infectious spores for the next year.”
In 1999, Alberta declared Fusarium graminearum to be a pest under the Pest Control Act. This put in place a series of regulations intended to slow or reduce the spread of the disease into central Alberta. Fusarium graminearum is a seed-borne pathogen and, along with infected crop residues, presents the most likely method of spreading the disease to non-infected areas.
Prevention
“The best management practices recommended to control the spread of the disease include testing next year’s seed to determine if it is infected, and if so, don’t use it,” says Brook.
Other management practices:
- Use seed treatment with activity on fusarium species on all cereal seed.
- Clean equipment of any crop residue between fields if fusarium has been found in a field.
- Use a crop rotation of at least two years between potentially susceptible cereal crops.
- Increase seeding rates to limit stooling and reduce the time the cereals flower (reducing their susceptibility to infection).
- Use an appropriate fungicide to limit the infection if conditions are favourable to development of the disease (warm, humid evenings and days) and fusarium is known to be in the area.
- Avoid irrigation during flowering.
- Bury affected cereal crop residue.
- Control volunteer cereals and grasses in the headlands and around fields.
